16 deep 18 wide...middle posts on the 16ft run.How far is the span between the posts ? Trying to figure in my head how to go about building the beam for the roof to sit on at the posts . The rest is easy peasy. You going to carry the shingles out over the roof or something else?
Vaulted.. or enclosed ceiling?
Metal roof on house....same on deck.
Open ceiling with a couple of fans.